The Justice Department is investigating whether Las Vegas Sands Corp., owned by high-profile Republican donor Sheldon Adelson, broke federal law by failing to report millions of dollars of potentially laundered money transferred to its casinos by two high-rolling Las Vegas gamblers, according to the Wall Street Journal.

The U.S. attorney’s office in Los Angeles is investigating deposits made in the mid-2000s by a Mexican pharmaceutical businessman, later indicted for drug trafficking in 2007, and a California executive with Fry’s Electronics, who later pleaded guilty to taking illegal kickbacks, the newspaper said, citing lawyers and federal officials working on the case.

The Journal said there were no indications that the investigation included actions by Adelson, Sands’ chief executive and a major political donor for the Republican Party. Adelson has pledged to spend as much as $100 million to help Republican candidates in this election cycle.

Federal investigators have begun focusing on casinos amid concerns that the industry’s lax financial systems could bHase used for money laundering and other illegal activities, according to Justice Department officials cited by the Journal.

Sands Corp. did not immediately return calls from the Associated Press on Sunday. A company spokesman, Ron Reese, told the Journal that the company believes “it has acted properly and has not committed any wrongdoing.”